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Interview: Larry Robertson

Interviewer: Arlene Van Dyke
Interviewee: Larry D. Robertson, Mycologist
                      Mycotech Biological, Inc.
Date: October 5, 2001
Place: IAQA (Indoor Air Quality Association) Conference

Q: Please tell me what you do? What is your job?

A: At this point my job is multifaceted in the sense that we have MBI which is an analytical laboratory that provides support services for the indoor air quality community. We specialize in the identification of microbial organisms. MBI was formed 18 years ago back when nobody knew what to do with this information or even how to get it. So it was almost like a natural default to doing consulting work, to go out and perform the investigations. So there is at least a portion of our business that is involved with investigations. But as of early last year we have tried to cut that completely out of MBI. It is another operating entity now that is a consulting network with existing consultants that I have known over the years, particularly like yourself. If we get a call from somebody in North Carolina that has a problem, we are not going to go to North Carolina. It would not be cost effective. We are trying to build that consulting network to be able to put people onto qualified consultants to perform those services in a cost effective manner.

I do have some continued and emerging roles in education. I have always been committed to educating the industry. That is primarily why I was involved with IAQA for so long. Some of the programs that have recently been put together and offered through that association I have received a great many compliments on, and I think I am going to continue to play some type of role in the education and hopefully the proper development and direction of the industry.

Q: When cultures are done, when you do the analysis, what kind of information is reported?

A: A report that someone gets on their home could involve a variety of things that measure or evaluate things as simple as temperature and relative humidity all the way through volatile organic compounds (VOCs), or dust, or other types of contaminants, which might be microbiological. Mycotech specializing in the microbial aspects of it would generate analytical information that might be culturable based, it might be just raw data that is uncultured, such as scrapings, bulk samples and things of that nature that would essentially identify organisms or concentrations of the organisms. The strategy that we try to empower the individuals that are collecting the samples with would be to identify the two types of sample categories. That being the source sample and an aerosol sample, and to try to utilize the source sampling to identify what organisms are there at a visible or suspected contamination site and as compared to what concentrations and populations exist in the air. Together those two pieces of information provide some guidance with regard to the overall quality of the environment; whether or not remediation is necessary, whether or not the aerosol levels at that point in sampling were atypical or unusual. This is typically the kind of data that would be rolled into the microbiological aspect of a report.

Q: When a person sees mold, one of the first things they ask is "Can you come and tell me what kind of mold it is?" Is that possible to look at a mold with the naked eye and say this is what it is?

A: To look at a mold through the naked eye and identify specifically what it is, is not possible. That identification has to be done through microscopic evaluation. Certainly there are categories of fungi, and we can narrow them down into what we think it might be but it is always a guess. I continue to this day to test myself on how good I am at that. Even at seeing these fungi for 30 years now, I cannot absolutely, positively confirm these fungi by the naked eye every time. So my default on that question is, if I can't do it after looking at these organisms for 30 years on a day to day basis on all these different building materials, I don't believe that anyone can do it with any precision or accuracy. I don't believe that it can be done.

Q: Do you think people should be worried about all molds or just specific molds?

A: In general, people need to be concerned about all mold but the concern needs to be tempered by a rational response. In other words, we have to understand that these fungi are everywhere and we have been living with them for all time. And there is no environment, indoor environment or outdoor environment, that is free of these organisms. If there is one thing 20 years of inspecting residences and buildings have shown me it is that I can find these organisms in every building. In my opinion, there is not a building or a residence that does not have active fungal contamination in it to a certain degree. However, that being on one side of the spectrum the other side of the spectrum are situations where abnormal levels of fungi and fungal growth exist and where the line is between the two is very undefined at this point. A lot of the problems are hidden and unknown to the occupants and they don't know these exposures are actually taking place. On the other side of that spectrum are substantial contamination issues or hidden contamination issues that are of some volume that really do generate concern.

Q: You don't feel that mold should be ignored but something should be done about it?

A: I don't feel that you can ignore mold, at the same time I don't think you can ignore other critical issues in terms of your obligation and responsibility in ownership or maintenance of property. In other words, if you own a house and you see that dust is accumulating, you have an obligation in terms of the hygiene of the home to clean it up. And if you don't then you are actually contributing to a problem or a potential problem. And if you have a leak in the roof or on a window that you know exists and you don't address it and that leak ultimately results in the presence of a fungal growth, you are essentially allowing this environmental event to take hold and, in my opinion, it does require an appropriate response. The initial response does not need to be a knee jerk, hysterical kind of thing. It needs to be a common sense, rational approach.

Q: What parts of the home can be affected by mold?

A: Theoretically there is no part of the home that could not potentially be affected by mold. The roof area could be affected by intrusion events, exterior perimeter walls could be affected by intrusion events resulting from the roof or from inappropriate flashing either up at the eaves or around the windows. There are some design considerations with regard to vapor barrier placements inside of the walls that could render them susceptible. Drainage around the house and training water back to the house, inappropriate seals around foundations or inappropriate ventilation in sub-foundation crawl spaces, weeping through basements, etc., all essentially render the home susceptible to mold growth due to some type of water infiltration. Then within the home itself always you have the potential of a catastrophic water release from a plumbing event, from some weather event or weather related abnormality. But you also have the isolated leaks that could occur with regard to showerheads, shower pans, commode backups or plumbing backups. And then central to all of that is the air-conditioning system which is an inherent microbial incubator that can without the proper long-term sanitation and periodic appropriate filtration can actually foster the growth of these organisms.

Q: In your research, what type of individual have you found to be more susceptible to mold toxins or mold allergies?

A: I don't think there is a clear line. My segue into indoor air quality and microbial related events was because I suffered a hypersensitivity reaction to a mushroom. I had spent my entire college career learning how to grow mushrooms. The first two and a half years after leaving college I spent working for a commercial mushroom facility, growing Agaricus campestris, which is the common button mushroom, with the idea of going back to Texas and buying an old school and converting the classrooms into mushroom chambers and growing exotic mushrooms. I grew three varieties of exotic mushroom, one of them being Pleurotus ostreatus. The spores of that mushroom gave me a hypersensitivity reaction. I went through mycological school for six years. I worked at a mushroom farm for two years. I was involved with exposure to Aspergillus fumigatus, streptomyces, the types of fungi I was exposed to were across the board and I had never had a hypersensitive exposure until this one mushroom that all of a sudden came out of nowhere. There is no way to predict that. There is no way to predict what an individuals reactivity is going to be to an allergic reaction like that. The severity of their allergic reaction, of the toxic reaction, or their potential compromization for a disease causing situation, although mostly rare, are caused essentially when the immunological system begins to fail.

Q: Do you think people should leave the home if they have mold in it or at what level of does the exposure become dangerous?

A: I tend to look at whether or not the evacuation of a residence or a building should occur by looking at three factors. (1) Is there a substantial presence of an active fungal source in the residential building, can I see fungi beyond just what is along the edge of the refrigerator seal? Is there another reservoir of fungus there that should not be there, that is unusual and that is significant. (2) The documented elevated aerosol levels or the potential for those elevations to occur sporadically or periodically even though the tests that I have do not confirm that. (3) The presence of symptoms. If there are those three things going then I don't automatically say "Get out". I immediately start looking for other kinds of issues that exist. For example if it is a two bedroom, one bathroom home and there is contamination in the bathroom, we could isolate that contamination and the people could stay in their home but they would lose their bathroom. So in fact they can't stay in their home. And in a situation like that, even though there may not be any medical symptoms at that time, the situation might force an evacuation because we want to localize the contamination. But because the people can't use their bathroom anymore it forces an alternative living situation. So there are other components that come into such a decision but just to visually see mold in the house and declare that someone should be evacuated, in my opinion, is highly escalated and almost alarmist.

Q: The water or "aW content", when you are looking at a species in an investigation, can you determine how much water had to be there to get the species growth?

A: It is the amount of water that triggers the growth of a particular species. Once the species starts to grow the amount of water can vary. Let's say for example we had a fungus that had to have a 0.7 water activity to grow. What that really means is it needs a 0.7 water activity for the spores to germinate. That 0.7 aW has to be sustained long enough where the fungus can germinate, develop a mycelium that penetrates the material and then once that occurs and it becomes well established, the water activity can go back down to 0.5 aW. The fungus is still going to grow, it is just going to grow at a lower metabolic rate.

Q: Insurance companies ask us; Is this from previous water damage? How long has there been water damage?

A: Yes, they are trying to address causation and of course causation directly equates to whose going to pay for it. Some of those are easy and some of them aren't. You almost have to look at the sources of water, the patterns of water that you can see and evaluate the presence of that fungus ecologically. But to attempt to time date a fungus is not appropriate. You really can't do that.

Q: Can you tie mold into health symptoms? Homeowners want to know is this causing my headaches, or my respiratory problem, or my allergies?

A: Can I do that in my own mind? I would say absolutely yes I can do that. Can I do that from a professional standpoint. No I cannot do that because I am not a medical doctor to be able to say symptomatically what is going on with someone.

Q: Dr. Rinaldi mentioned the closer the speciation you can give the doctor the better it will be for the patient?

A: That is correct. The relationship of allergy exposure is well documented. Exposure to abnormal levels or even normal levels of these things on a chronic basis can cause allergic reactions in people. So the allergy relationship becomes much easier for a physician to make that leap with. It is a little bit more difficult in terms of an invasive disease and mycotoxin kinds of things. For example in Dr. Rinaldi's presentation today there was a case of an individual that did not have an organism exposure, who was in a clean room but got exposed to something and then contracted this organism. He was able to make a specific environmental leap to something inside of the hospital. The real ability to do that in an environmental situation where we do not have someone confined in a special area like that clean room, then we do not know whether it came from the floor sweep, the wind that came by the window or any other potential sources. And that organism can exist in any number of sources. It was a unique case with respect to the patient in Dr. Rinaldi's talk.

Another is, a perfectly healthy person goes into a cave where there are bats and histoplasma or aspergillosis, it gets stirred up, they inhale it and come down with a disease. Those are pretty much no brainers. But the kinds of diseases that we are talking about in the general environment per se, we do not know whether it is coming from the home air-conditioner, the carpet, or the automobile air-conditioner, because these organisms are all there anyway. We just don't know which one it came from. There have probably been 15-20 cases over the 20 year period, prior to the time that it became attractive for people to start suing, where occupants have clearly had symptoms but all the air testing we did showed nothing. Yet further investigations revealed hidden substantial reservoirs of fungal contaminants. Indicating to me that there is a mycotoxin airborne volatile mycotoxin exposure out there. We were not detecting it by Andersen, Zeflon or any of the other methods and yet when the appropriate abatement was done those people got better. I don't have to be a doctor to say that it happened, but I know what I saw and I have seen it repeatedly enough to know there is a cause and effect event going on with mycotoxic VOCs.

Q: There are definite symptoms tied to mycotoxins then?

A: Yes, I think basically a lot of them are the "sick building syndrome" kinds of symptoms that are reported, low grade chronic headache and long-term lethargy. Much like you would get if you went into the old basement that smelled musty and moldy. There you have an odor threshold where you are able to detect it. But I am suggesting those things can actually exist at odor levels below odor thresholds so you do not detect the odor but you do develop the headache.

Q: Can ozone kill mold?

A: I have not seen any compelling information to suggest that ozone can kill molds. There have been some studies that actually indicate ozone in certain concentrations can actually stimulate mold growth. Some of the ozone studies that have come out of California and the effect of agriculture exposed to ozone has stimulated the growth of fungi. The wealth of scientific information out there indicates that there is absolutely no effect. There is a lot of anecdotal information out there in the private sector that say these things really work. When I am pressed to make a decision, I always default to the scientific side indicating that there is no evidence that these things (ozone machines) kill fungi. But I also add the anecdotal information that if there is a visible growth of fungi present there is no way the ozone is going to get rid of that visible growth. It has to be remediated, it has to be removed.

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